Portable floors, such as dance floors, for example, provide versatility and efficiency in the use of floor space. A typical portable dance floor includes a number of portable sections which may be conveniently connected for use when a dance floor is required, and then disconnected and stored in a storage space when not in use. Typically, these portable sections include wooden parquet panels which provide an aesthetically pleasing surface for dancing, mounted over a sub-layer having cooperating, metal tongue and groove coupling elements located respectively around the perimeter of the respective sections for connection in side-by-side relationship with adjacently situated sections. Exterior channels border the outer perimeter of the connected floor sections, and taper downwardly at an angle to the base surface upon which the portable dance floor is supported.
A prior portable dance floor of this type is disclosed in Bue et al. U.S. Pat. No. 3,310,919. This patent discloses a lockable tongue and groove structure for connecting adjacently situated sections. This locking structure includes a groove defining channel element associated with one floor section and a tongue defining element associated with an adjacent section. Access holes are provided in the parquet panels situated along the length of the sections above the groove elements. The access holes are aligned with corresponding bores in an upper leg portion of the channel member which forms the groove. An externally threaded set screw is inserted from above the dance floor surface into each access hole and aligned bore until the bottom of the set screw contacts and compresses the inserted tongue, thus locking the sections together. Typically, the tongue has a thick forward end and is tapered rearwardly to a thinner crosssection at its juncture with the floor section on which it is mounted.
It is also known to utilize, in each aligned access hole and bore, a sleeve-like insert. External threads permit it to be threaded into the floor section. Internal threads are provided for an externally threaded set screw threadably received within the insert. Typically, the set screws have an Allen socket and are accessible for tightening from above the floor through the access holes.
Twisting of such a set screw moves it downward within the insert and into contact with the tongue of an adjacently situated floor section, thereby locking the tongue in place between the upper and lower channel legs forming the groove, and connecting the adjacently situated sections in side-by-side relationship.
Since the groove defining channel is usually aluminum and thus soft, threads in it are easily stripped. Set screws used without inserts tended to strip out threads in such channels. The harder metal insert has been an attempt to eliminate that problem.
The conventional tongue and groove coupling between adjacently situated floor sections has proven convenient for assembly and disassembly. However, these particular locking mechanisms suffer from a major disadvantage resulting from the tendency of the set screw, the threaded insert when used, or both the insert and the set screw to back out or strip out upwardly above the upper panel or floor surface of the connected sections, particularly when improperly tightened or untightened by the user. Upward protrusion of the set screw or the insert above the floor exposes the insert or screw to damage from adjacent sections when handled for storage. This could result in bending of the screw or insert when hit by a separate section, or the screw or insert could cause surface damage to an adjacent panel.
It is therefore an object of this invention to provide an improved simple and effective locking mechanism for maintaining a tongue and groove coupling between adjacently situated portable dance floor sections.
A further objective of the invention has been to prevent stripping of the threads associated with the tongue and groove locking device.
It is another object of this invention to provide a simple locking mechanism for locking a tongue and groove coupling between adjacently situated portable dance floor sections in which the components of the locking mechanism are not susceptible to upward protrusion above the dance floor surface.